The present invention is directed to pressure-sensitive adhesive compositions that exhibit high adhesion to high energy surfaces such as aluminum and possess high tack and outstanding holding power at elevated temperatures. Two key monomers are used in combination in the pressure-sensitive adhesives of this invention to impart unique properties to the resulting polymers. The monomers are at least one glycidyl monomer in combination with at least one N-vinyl lactam.
The use of glycidyl monomers in pressure-sensitive adhesive has been disclosed in the art.
U.S. Pat. No. 3,284,423 discloses creep-resistant pressure-sensitive adhesive compositions comprising 35-75% by weight alkyl acrylate esters containing 6-15 carbon atoms, 10-60% lower alkyl acrylate, 0.1-10% by weight of an ethylenically unsaturated carboxylic acid and 0.1-10% by weight glycidyl ester.
U.S. Pat. No. 3,893,982 discloses an interpolymer comprising 0.1-15% parts of an ethylenically unsaturated carboxylic acid, 0.1-2% parts of a glycidyl monomer, 35-84.9% parts of an alkyl acrylate or methacrylate and optionally a monomer selected from the group consisting of alpha-olefins containing 2-10 carbon atoms, vinyl esters of alkanoic acids containing 3-10 carbon atoms, ethyl and methyl esters of acrylic and methacrylic acids, acrylonitrile, methacrylonitrile, styrene and vinyl chloride where the polymer has a weight average molecular weight in the range of 10,000-500,000 and between 0.01 and 1 parts by weight per 100 parts of the copolymer of 1,3-bis(dimethylamino)-2-hydroxypropane to cause the cure of the epoxy group.
The art has also taught the use of N-vinyl lactams in polymers.
U.S. Pat. No. 3,728,148 discloses a pressure-sensitive adhesive for electrical insulating applications comprising of a copolymer of 65-90% by weight of an alkyl acrylate ester, 10-30 by weight of a N-vinyl lactam and 0-20% by weight of a modifying monomer which is copolymerizable with the above. Acidic monomers and amides are excluded as they are claimed to cause undesirable corrosion.
U.S. Pat. No. 4,181,752 discloses an interpolymer containing 87% by weight isooctyl acrylate, 8% by weight vinyl pyrrolidone, 3% by weight acrylic acid and 2% by weight acrylamide.
U.S. Pat. No. 4,364,972 discloses a pressure-sensitive adhesive tape made by copolymerizing an alkyl acrylate ester with 15 to 50 parts by weight of vinyl pyrrolidone and having a K-value greater than 100 and when crosslinked has a gel-swell in ethyl acetate in excess of 600%. Advantages claimed are good adhesion to automotive paints, rubber and plastic foam layers.
U.S. Pat. No. 4,310,509 discloses a 90/10 2-ethyl hexyl acrylate/vinyl pyrrolidone copolymer for making a pressure sensitive adherent for complexing with iodine for anti-microbial activity.
European Patent Application No. 130080 discloses an emulsion polymerized pressure-sensitive adhesive comprising 2-20% by weight N-vinyl lactam and an alkyl acrylate ester. The claimed use is good adhesion to skin under hot and humid conditions.
U.S. Pat. No. 4,370,380 is directed to a blend of two polymers. One is a copolymer of 88-99% by weight of an alkyl acrylate ester with 1-12% by weight of a carboxylic acid with a glass transition temperature (Tg) of less than 0.degree. C. The second polymer is either a homo or a copolymer of N-vinyl lactam with a Tg of 20.degree.-150.degree. C. The blend ratio is 70-99% by weight of the first polymer with 1-30% by weight of the second polymer. The resultant pressure-sensitive adhesive is disclosed to have moisture permeability.
U.S. Pat. No. 4,150,197 discloses a water vapor permeable pressure-sensitive adhesive comprising a copolymer of 79-89% of butyl acrylate, 10-20% by weight of N-vinyl lactam and 1-5% by weight of an acidic comonomer.
None of the patents or applications discloses a copolymer containing both a glycidyl monomer and N-vinyl lactam monomer.